The present invention relates to a method and apparatus for opening a gas container that via a filling opening is connectable to an air bag of an impact protection means for the interior of a motor vehicle. The filling opening is closed off by a safety disc.
Inflatable air bags serve to protect the occupants of motor vehicles. Their effectiveness depends, among other things, upon the functional reliability and speed of the their release mechanism.
DE 195 13 242 C2 discloses a filling device for the air bag of an impact protection means. Upon triggering or release of the impact protection means, the safety disc of a gas container is weakened and thereby made to burst or crack under the pressure of stored gas. This is accomplished by means of an electrode that is spaced from the safety disc and operates with sparks, or by an electrode that is in contact with the safety disc and operates by resistance heating.
The electrode of the aforementioned reference is ring or cylinder shaped, and has a large effective surface area relative to the safety disc.
The drawback of using a spark effect is the high firing voltage that is required, which amounts to 3 KV at only 0.8 mm electrode spacing. In the manner of spark ignition this can be produced with an ignition coil, the continuous current of which is interrupted at the moment of ignition to induce a high voltage pulse. However, already for energy reasons, a continuous current in a motor vehicle does not even come under discussion.
A rapid heating of the safety disc by electrical resistance presumes in the present situation a high electrical power, which requires a large energy storage means.
It is therefore an object of the present invention to provide a method and apparatus for reliably, rapidly and with little structural expense being able to open the gas container of an impact protection means for the interior of motor vehicles, thus overcoming the drawbacks of heretofore known devices, namely considerable structural expense, a require for a lot of space, and a relatively long ignition delay.